>What's a megapixel?
A measurement unit indicating the amount of information a camera reproduces. The higher the number, the more detail rendered. Most cameras allow you to adjust resolution to maximize quality or storage space. For instance, a 6mp camera yields sharper detail, while using its 3mp option crams more pictures onto the memory card.
>How many megapixels do I need?
At least 4, but as in so many things, size matters less than ability. We've found excellent 5mp cameras that cream poor 7mp models. How do you know which is which? Check out the over-the-top tests on www.dpreview.com or www.steves-digicams.com. Or take this shortcut: We've yet to see a bad 4mp-or-higher Canon, Nikon, or Olympus.
>What's the difference between JPEG, TIFF, and RAW?
They're all file formats in which you can save your images. JPEG is the most ubiquitous and universally accepted. TIFF is a bit higher in quality, but not supported by some software and print labs; they're also bigger files, which makes them slow to download. RAW is for the do-it-yourselfer with the software to manipulate the raw data.
>What's a memory card?
Think of it as a Zip drive for your camera. These postage-stamp-size storage devices typically hold 256KB to 4GB of memory-or dozens to thousands of images.
>Which type of card should I buy?
It's a veritable alphabet soup: SD, xD, CompactFlash, Memory Stick, and so on. But the answer is simple: Pick the camera you like, then buy the card it takes. Some formats are cheaper for more memory, but who buys tires before picking a car?
>What's the best battery type for backpacking?
All else being equal, go with the camera that has rechargeable lithium batteries, which work better in the cold than nickel metal hydride and alkalines.
>Optical or digital zoom?
No-brainer: Optical. Digital means that the camera magnifies the data from only a section of the image, and it looks as bad as that sounds. 3x optical zoom is basic, and best for close-ups. 6x starts to capture far-off detail, like a bear moving across the opposite side of a meadow.
>Is there a perfect "compromise camera?"
No. While most major makers offer 8mp compacts with basic DSLR features, these pricey models still have the same shutter-lag, focus-speed, and low-light issues that other compacts do. They also tend to burn through batteries, but lack lens flexibility. Our advice? Choose DSLR for pro-quality images and control, and compact for weight savings and ease of use.